1. Field of the Invention
This invention relates to a recording device, and more particularly, to a recording device such as an impact type electronic typewriter or the like that uses an ink ribbon and operates by vertically shifting the ink ribbon to use different regions along the width of the ink ribbon and position it in a non-printing position.
2. Description of the Prior Art
Heretofore, this kind of recording device often required a ribbon-shifting mechanism which shifts the ink ribbon downward to a non-printing position so as not to hinder reading of recorded characters between printing strikes of the hammer. When printing is to take place, the ribbon shifting mechanism shifts the ink ribbon upward and in front of a recording head. Furthermore, in the high-end categories of this kind of device, as disclosed in U.S. Pat. No. 4,494,886, there has been adopted a configuration in which a so-called end sensor for detecting an end of the effective portion of the ink ribbon is provided, and recording is automatically stopped when the sensor has detected the end of the ribbon.
In this kind of device, it is common, such as shown in FIG. 7, that the width of the ink ribbon 19 is a little larger than the height of the largest characters, such as shown by A-F, and in that case the entire width of the ribbon is used for the printing of one character.
Recently, however, there have been developed devices in which a wide ink ribbon is used in order to increase the area usable for printing. In these devices, the ribbon is shifted in the vertical direction in plural stages, and thus printing can be performed by utilizing the ink ribbon width in a multistage way. FIG. 8 illustrates an applicational example thereof. In FIG. 8, and ink ribbon 9, the width of which is a little larger than 3 times the height of the largest characters, as shown by characters A-F, is used. The ribbon is divided into 3 rows each of which is used for the printing of one character, and printing is performed by successively shifting the ribbon in the order of the upper row, middle row and lower row as shown by arrows. Because the width of the ribbon 9 is larger than three times the height of the largest of the printed characters, there exists a non-printing region along the top and bottom edges of the ribbon 9.
In such devices for performing multistage printing, a motor which performs exact position control, such as a stepping motor or the like, is used for the shift control of the ink ribbon vertically; i.e. upward and downward in the direction of its width, and thus shift control is performed with a high accuracy. Now, in such devices, the position of the ink ribbon is not set when the power supply of the device is turned off. Hence, it is necessary to shift the portion of the ink ribbon used for printing precisely to a predetermined initial position (waiting position under non-printing situation) immediately after the power supply of the device has been turned on.
Two methods of achieving the above described objectives have been disclosed in Japanese Patent Publication No. 32317/1984. In one of these methods, the position of the usable portion of the ink ribbon in the direction of the width of the ribbon is detected by an exclusive sensor, the detected result is stored in a memory fed by a backup power supply, and the information of the position in the direction of the width of the ink ribbon portion to be used is located in the memory and is output to a control system when the power supply is turned on. In the other method, there is provided initializing means, which is operated when the power supply is turned on, and an ink-ribbon cassette housing an ink ribbon is pivoted to a predetermined position in the direction of the width of the ribbon, and at the same time, the ribbon is advanced in a longitudinal direction in order to prevent reusing the same portion of the ribbon.
In the former method described above, however, there is a problem that a sensor for detecting the position of the ink ribbon in the direction of the width, a memory for storing the detected result and a power supply for backup are needed, and this causes increase in cost.
In the latter method, there is also a problem that the provision of the initializing means causes an increase in cost.